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HOMESTEAD, Fla. — This week, teams of engineers from around the
world are competing in the DARPA Robotics Challenge Trials, a
prestigious robotics competition that will showcase some of the
most advanced machines in development. From two-legged creations
that resemble humans to bots that drive around on tracks like a
tank, the contest boasts a diverse range of robot designs.

The
DARPA Robotics Challenge Trials is being held today and
tomorrow (Dec. 20-21) here at the Homestead Miami Speedway. The
17 participating teams will be evaluated based on how well their
robots tackle eight challenging tasks, which are designed to
mimic actions that robots could perform in place of human
responders in the wake of natural or man-made disasters.

The robots on display in Florida will be various shapes and
sizes, with each robotic design having inherent benefits and
drawbacks, he added. As such, it can be difficult to predict
which type of robot may prevail at the trials.

Machines that resemble humans, the thinking goes, may operate
more seamlessly in a world built around human specifications,
such as
being able to wield tools designed for human hands. But,
there are downsides, said Chris Jones, director of strategic
technology development at iRobot Corporation, the Bedford,
Mass.-based company behind the well-known robotic
Roomba vacuum, which can autonomously clean floors while
avoiding obstacles around the house.

"Legged [robots] are interesting, but technically very
challenging to accomplish," Jones told LiveScience. "Yes, you can
build humanoid robots, and yes, they can fit in the human
environment, but can you do it in a cost-effective fashion to
justify the inherent complexity?"

iRobot is not competing in the Robotics Challenge, but the
company did design a three-fingered
robotic hand that will be used by several groups that
qualified for the DARPA trials.

Tackling mobility

With a humanoid robot, some of the most challenging issues
involve figuring out how it will move around effectively, said
Rodney Brooks, founder and CTO of Rethink Robotics, a commercial
robotics company based in Boston, Mass. (Rethink is not
participating in the DARPA Challenge.) Brooks, who was a
professor of robotics at MIT, also co-founded iRobot in 1990, but
he is no longer affiliated with the company. [ Super-Intelligent
Machines: 7 Robotic Futures ]

"You have to balance, and that's really hard," Brooks told
LiveScience. "There's also a lot of work to be done in figuring
out efficient walking algorithms to get good performance."

With four- and six-legged robots, maintaining balance is less
precarious. Similarly, robots on tracks are more stable when they
move, compared with two-legged machines.

"Tracked vehicles can get over rough terrain without having to
worry about where to put a foot down, or how to control the dozen
motors required for the walking motion," Jones said. "It's easier
that way to keep balance."

Pushing the limits

Right now, human muscles are also simply more agile than their
mechanical counterparts. This becomes particularly challenging
for larger,
humanoid robots, because their mechanical legs have to
contend with a greater distribution of mass.

"Building a big thing that walks is harder than building a small
thing that walks — things work differently on a micro scale,"
Brooks said. "It has to do with the strength to weight ratio.
This is why an elephant's legs are much weaker, relative to its
body mass, compared to an ant."

And then there's a clumsiness of sorts. "Where we are right now,
robots are roughly at the same level of dexterity and mobility of
a 1-year-old child," Pratt said. "They fall down, they drop
things out of their hands all the time — in general, they need to
try things many times to get them right. That's about where the
field is now."

Yet, DARPA is well aware that the robotics industry has a ways to
go before these types of machines live up to the imaginations of
Hollywood filmmakers and science-fiction writers, and the agency
hopes incentive-based contests like the Robotics Challenge will
spur continued growth in the field. But for now at the DARPA
trials, the robots that do walk on two legs will likely take slow
and deliberate steps, event organizers have said. Even the
multi-legged robots, and those that will move on tracks,
represent advanced technologies in a fledgling industry.

And, testing a variety of robot designs at the DARPA trials will
help engineers better understand which features work best in
different disaster scenarios.

"That's part of the point," Brooks said. "You take a bunch of
designs and see how far you can push them."